A. When a router receives a failure response, it stops querying authentication methods.
B. When a router receives an error response, it stops querying authentication methods.
C. If the router receives a failure response from an authentication method, it queries the next method.
D. The router does not differentiate between failure and error responses; the authentication process is always interrupted.
E. If it receives no response from the authentication method, a router will determine the error condition on its own; the router also has the option to proceed to the next method in a list if configured accordingly.

A. CEF switching is not needed for MPLS operation.
B. CEF switching is only needed to forward labeled packets.
C. CEF switching is needed on both ingress and egress interfaces on which MPLS is enabled.
D. Interface-level CEF switching is needed only on egress interfaces that are sending IP packets on which the egress LSR performs the label imposition process.
E. Interface-level CEF switching is needed only on ingress interfaces that are receiving IP packets on which the ingress LSR performs the label imposition process.